Customers who trade in a working iPhone 4 or 4S can earn a credit of up to $150, as determined by Best Buy, which then covers the $149.99 cost of a new 16GB iPhone 5. That price includes a $50 instant rebate effective until June 29.

Don't go throwing your iPhone 4 at Best Buy employees just yet, though. Qualifying buyers must be eligible for an iPhone upgrade with their carrier. So AT&T, Sprint, and Verizon users, make sure you check your wireless agreement before trying to pick up a new iPhone. When you buy, your contract will be re-upped for another two yars.

Those iPhone users who have kept their device in tip-top shape may be up for an added Best Buy bonus  If the company deems your phone worth more than $149.99, it will make up the difference with a store gift card. Check your iPhone's potential trade-in value with Best Buy's online pricing tool.

The big-box retailer's four-year-old program earned its highest volume of trade-ins during a similar promotion on June 1, inspiring the company to do it again starting today, according to USA Today.

Best Buy did not immediately respond to PCMag's request for comment. The company also accepts trade-ins for video games, computers, tablets and e-readers, MP3 players, cameras, camcorders, musical instruments, DVDs, and CDs.

Stephanie began as a PCMag reporter in May 2012. She moved to New York City from Frederick, Md., where she worked for four years as a multimedia reporter at the second-largest daily newspaper in Maryland. She interned at Baltimore magazine and graduated from Indiana University of Pennsylvania (in the town of Indiana, in the state of Pennsylvania) with a degree in journalism and mass communications.
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